In many electrically operated motors which have been conventionally known, electromagnets consisting of a coil winding are used for both a rotor and a stator. In addition, there is a stepping motor, wherein a magnetic body or a permanent magnet is used for a rotor and electromagnetic coils are used for a stator. However, this stepping motor needs a special device to control the phase.
The present inventor proposed the following motor in Japanese Patent Application Laid-open No. Hei 10-126987. The motor comprises a rotor rotatable about an axis of rotation and electromagnetic coils arranged around said rotor, said rotor is equidistantly sectioned into a plurality of regions in a circumferential direction, each region is provided with a part wherein a plurality of permanent magnets are adjacently provided and another part wherein no permanent magnet is disposed, said permanent magnet is disposed inclining against a radial line which extends outward from said axis of rotation, said rotor includes a disc and a circumferential plate which is connected to a circumferential edge of said disc, and said plurality of permanent magnets are arranged on the inside of said circumferential plate.
As described above, the rotor is rotatably supported and has a plurality of permanent magnets disposed inclining against radial lines which extend outward from said axis of rotation, and when the electromagnetic coils are not supplied with electric current, the rotor stops after it rotates due to magnetic action between magnetic lines of force formed by a plurality of permanent magnets and the electromagnetic coil to a position wherein a permanent magnet located at an end of a plurality of permanent magnets faces to the electromagnetic coil. Under this condition, if the polarity of the magnetic coil is changed to the polarity which is the same as that of the facing permanent magnet, the magnetic body and the permanent magnet repulse each other, and the rotor rotates.
In such a motor, in order to continuously and effectively rotate the rotor, it is necessary to detect that the permanent magnets on the rotor locate at a predetermined positional relationship relative to the electromagnetic coils and control electric current supply to the electromagnetic coils.
In Japanese Patent Application Laid-open No. Hei 10-248288, proposed is a device wherein rotors L1 and L2 are mounted on a spindle M, magnetic sensors H1 and H2 are disposed between an iron core O1 and the rotor L2, the iron core O1 facing the rotor L1 has driving coils K1, K3 and K5, the iron core O1 facing the rotor L2 has driving coils K2, K4 and K6, the rotor L1 and L2 have permanent magnets J with aligned magnetic polarities disposed thereon, the driving coils are connected in order of K1, K2, K3, K4, K5 and K6, the driving coil K1 has a lead line X, the driving coil K6 has a lead line Y, transistors Tr1 and Tr3 and transistors Tr2 and Tr4 are disposed between power source V and power ground G, respectively, inverters IC A1-A6 are disposed between the transistors Tr1-Tr4 and magnetic sensors H1 and H2, the transistors Tr1-Tr4 have diodes D2, D3, D4 and D5 bridged therebetween, a double toggle switch is disposed between the power source V and the magnetic sensors H1 and H2, the lead line X from the driving coil K1 is connected between the transistors Tr1 and Tr3, and the lead line Y from the driving coil K6 is connected between the transistors Tr2 and Tr4.
In this device, the magnetic sensor H1 which detects the N Pole of the permanent magnets J outputs and a digital low signal is transmitted to the inverters IC A1, A2, A4 and A6. The input signal is inverted in the inverters IC, and the output of the inverters IC A1 and A2 becomes a digital high signal. Further, the signal input into the inverters IC A4 and A6 is inverted twice, and the output of the inverters IC A3 and A5 becomes a low signal. The transistors Tr1 and Tr2 are PNP transistors, and transistors Tr3 and Tr4 are NPN transistors.
The transistor Tr1 which receives the output signal of the inverter Ic is not energized since it is in off condition. The transistor Tr2 becomes in on condition when it receives low signal and is energized, the transistor Tr3 becomes in on-condition when it receives high signal and is energized, the transistor Tr4 is in off-condition and is not energized, and when low signal is input into the inverters IC A1, A2, E4, and A6, the transistors Tr2 and Tr3 are energized and electric current flows from the lead line X toward the lead line Y.
Contrary to this, when digital high signal is input into the inverters IC A1, A2, A4 and A6, the transistors Tr1 and Tr4 are energized and electric current flows from the lead line Y toward the lead line X.
When electric current flows from the lead line X toward the lead line Y, the side of the driving coil K1 facing the rotor becomes S pole, and the side of the driving coil K2 facing the rotor also becomes S pole. Further, all the sides of the driving coil K3, K4, K5 and K6 facing the rotor becomes S pole. The thus appeared S pole and the S pole of the permanent magnets J repulse each other, and the rotors L1 and L2 rotate in a clockwise direction by 60°, where the output of the magnetic sensor H1 is reversed, and electric current flows from the lead line Y toward the lead line X. Then, the side of each driving coil facing the rotor becomes N pole which is reverse to the former polarity. When the N pole repulses the N pole of the permanent magnets J and at the same time attracts the S pole of the permanent magnets J, the rotors L1 and L2 further rotate in a clockwise direction by 60°. Repetition of these operations, the rotors L1 and L2 continuously rotate in a clockwise. The double toggle switch S changes the operating magnetic sensor from H1 to H2, so as to rotate the rotors in an opposite direction by changing the switching timing.
In the device disclosed in Japanese Patent Application Laid-open No. Hei 10-248288, energizing and dis-energizing of the transistors Tr2 and Tr3, and Tr1 and Tr4 are changed by means of the signal from the magnetic sensor H1 or H2, and electric current flows from the lead line X toward the lead line Y, or from the lead line Y toward the lead line X. Theoretically, the electric current flow from the lead line X toward the lead line Y and the electric current flow from the lead line Y toward the lead line X do not occur simultaneously. However, actually, depending on the component characteristics of the transistors Tr1 to Tr4, energizing of the transistor Tr2 and Tr3 and energizing of the transistors T12 and T43 may be overlapped, and as a result, electric current does not flow in the motor but passes through from the electric power V to the power ground G, and thus there is electric current which does not contribute to rotation of the motor.
Such passing through electric current causes problems that the output torque of the motor decreases, the rotation of the motor becomes unstable and the efficiency of the motor decreases. The problems become remarkable as the rotational speed of the motor becomes high.
It is an object of the present invention to obviate the above-described problems and provides a motor which can further enhance the rotational speed and by which higher efficiency can be achieved.
Further, in Japanese Patent Application Laid-open No. Hei 10-126987, proposed is a production method of a motor characterized in that:
a plurality of radial lines are drawn at an equal circumferential angle from a center point;
outlines of permanent magnets of a rectangular section are drawn at a predetermined inclination angle relative to said radial line from starting points on said radial lines locating at a predetermined distance from the center point;
a jig having a recess connecting outlines of said permanent magnets is prepared;
a plurality of permanent magnets are put along the recess of said jig; and
after relative position of said plurality of permanent magnets is fixed, said permanent magnets are mounted on a rotor body to produce a rotor.
Even when the production method disclosed in the above-described Japanese Patent Application Laid-open No. Hei 10-126987 which uses a specially designed jig is applied, since a plurality of permanent magnets having a rectangular cross section are disposed side by side, the sides of the permanent magnets closely and magnetically attract each other when permanent magnets having large magnetic strength are used. Accordingly, high assembling technique is still required for putting a plurality of permanent magnets inclining relative to the radial line extending from the center point and putting ends along the circular recess. Thus, the motor production efficiency is still low.
Further, in the rotor disclosed in Japanese Patent Application Laid-open No. Hei 10-126987, a plurality of permanent magnets are arranged on a flat circular disc. As a result, the permanent magnets may hit the circumferential plate due to the centrifugal force caused by the high speed rotation, and the circumferential plate is bulged or broken. Thus, there is a problem that the high speed rotation of the motor is limited.
It is another object of the present invention to obviate the problems inherent to the rotors disclosed in Japanese Patent Application Laid-open No. Hei 10-126987 that assembling is not easy and that there is a limit for the high speed rotation. Thus, the present invention provides a magnetic motor which can be assembled without requiring special skill with high production efficiency, and which has large strength, and which can be rotated at a high speed.